1. Technical Field
The present invention relates to an enclosure for liquid lubricated rotating elements, wherein a first rotating element with at least one bearing lubrication fluid drainage point cooperates with a second rotating element.
2. Background of the Invention
Turbo units are often used for extracting energy from engine exhaust gases, wherein the turbo unit comprises an exhaust driven turbine which drives a compressor for compressing the intake air supplied to the engine, so called supercharging. A turbo compound unit is sometimes arranged after the turbo unit for extracting some of the remaining energy from the exhaust gases. One example of such a turbo compound unit is a second exhaust driven turbine which e.g. mechanically transfers energy to the drive shaft of the engine or the like.
The turbo compound unit normally comprises (includes) a shaft in a bearing with a rigidly mounted turbine wheel that can be driven at high speed by the exhausts, e.g. up to about 80,000 rpm. This speed is reduced by means of a gear train; and possibly other methods, down to a considerably lower speed and is transferred to the engine shaft via a fluid coupling which prevents torsional vibration occurring in the engine shaft to be transmitted to the turbine shaft. Normally, a very efficient lubrication of the turbine shaft bearing is needed in order to endure the high rotation speeds that occur. For this object, lubrication oil may be fed with an overpressure of about 1-5 bar to the turbine bearing.
It appears that the oil leaving the turbine bearing which is supposed to drain down into the crankcase, may hit the fluid coupling which is rotating with high speed, as well as other rotating parts. This results in a formation of a turbulent spray of drops that move in the radial direction outwards until they hit the surrounding surfaces. It has been discovered that these types of oil flows impede the rotation of the fluid coupling, which negatively influences the efficiency.